Method and apparatus for installing casing in a borehole

ABSTRACT

An apparatus and method for installing casing into a wellbore is provided. The apparatus includes a piston assembly which is engagable with a casing string to be installed into a wellbore. The piston assembly works in conjunction with a previously installed section of casing in the wellbore to create a hydraulic piston system to aid in the installation of the casing string to which the piston assembly is attached into a wellbore. More particularly, the piston assembly in conjunction with an intermediate casing is used to aid in the installation of a casing string comprising production casing. A method of operating the piston assembly is also provided.

FIELD OF THE INVENTION

The present invention relates generally to the process of running in casing into a borehole. More particularly, relating to a method and apparatus for running in casing into a borehole by utilizing a previously installed casing as piston cylinder.

In the recovery of formation fluids, such as oil, gas and mineral deposits, the drilling and completion of a well, whether it be vertical, deviated or horizontal, plays a vital role in the successful production of the formation fluids.

In recent years the practice of drilling deviated and horizontal wells have become more desirable over vertical wells due to a higher production of formation fluid. A deviated well is termed as a wellbore that is not vertical. The term usually indicates a wellbore intentionally drilled away from vertical. A horizontal well is termed where the departure of the wellbore from vertical exceeds about 80 degrees. Note that some horizontal wells are designed such that after reaching true 90-degree horizontal, the wellbore may actually start drilling upward. In such cases, the angle past 90 degrees is continued, as in 95 degrees, rather than reporting it as deviation from vertical, which would then be 85 degrees. Because a horizontal well typically penetrates a greater length of the reservoir, it can offer significant production improvement over a vertical well. The operation of drilling deviated and horizontal wellbores is well known in the art and will not be discussed here.

The rate of production or the amount of production of a well is directly related to the length in which the reservoir is penetrated. However, in deviated or horizontal wells it becomes increasingly difficult to run in casing as the length of the casing run in is increased. To increase the length of casing run into the reservoir many prior art devices have been implemented to attempt to increase the length of casing run in. One such device is described in U.S. Pat. No. 6,868,913, of which its entirety is incorporated herein by reference.

SUMMARY OF THE INVENTION

In accordance with the present invention, to provide an apparatus and method to increase the length of casing that can be run into a wellbore.

In general, in one aspect, a method of running in casing into a borehole having a previously installed section of casing is provided. The method including the steps of:

(i) providing a piston assembly;

(ii) engaging the piston assembly with a casing string to be installed into the borehole;

(iii) inserting the casing string with the engaged piston assembly into the previously installed section of casing; and

(iv) pressurizing the previously installed section of casing above the piston assembly with a fluid such that the piston assembly engaged with the casing string is forced to translate within the previously installed section of casing such that the casing string is pressed into the borehole.

In general, in another aspect, a method of running in casing into a borehole having a previously installed section of casing is provided. The method includes the steps of:

(i) providing a piston assembly;

(ii) engaging the piston assembly with a casing string to be installed into the borehole;

(iii) inserting the casing string with the engaged piston assembly into the previously installed section of casing;

(iv) pressurizing the previously installed section of casing above the piston assembly with a fluid such that the piston assembly engaged with the casing string is forced to translate within the previously installed section of casing such that the casing string is pressed into the borehole;

(v) equalizing pressure across said piston assembly; and

(vi) disengaging the piston assembly from the casing string.

In general, in another aspect, an apparatus for running in casing into a borehole having a previously installed section of casing is provided The apparatus includes a piston body having a forward end including an adaptor sub and an opposite rearward end, the piston body defining a longitudinal bore formed axially therethrough. A mandrill is slidably received within the longitudinal bore through the rearward end and is slidable within the longitudinal bore to a first position and to a second position. The piston body having a radial shoulder surface of a diameter to correspond to an interior diameter of the previously installed casing, such that when the piston body is positioned within the previously installed casing a sealing contact is made between the radial shoulder surface of the piston body and the interior surface of the previously installed casing. The piston body further defining at least one blind port hole formed therethrough from an exterior surface forward of the radial shoulder surface to the longitudinal bore, and defining at least one annulus port hole formed therethrough from an exterior surface rearward of the radial shoulder surface to the longitudinal bore, and wherein fluid communication is established between the at least one blind port hole and the at least one annulus port hole when the mandrill is positioned in the second position.

There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated.

Numerous objects, features and advantages of the present invention will be readily apparent to those of ordinary skill in the art upon a reading of the following detailed description of presently preferred, but nonetheless illustrative, embodiments of the present invention when taken in conjunction with the accompanying drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is a schematic view of a conventional land well casing architecture;

FIG. 2 is a schematic view of the preferred embodiment of the apparatus for running in production casing constructed in accordance with the principles of the present invention;

FIG. 3 is a partial cross-sectional view of the apparatus positioned within a previously installed casing with the mandrill in the first downward position; and

FIG. 4 is a partial cross-sectional view of the apparatus positioned within a previously installed casing with the mandrill in the second upward position.

The same reference numerals refer to the same parts throughout the various figures.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and particularly to FIGS. 1-4, a preferred embodiment of the apparatus of the present invention is shown and generally designated by the reference numeral 10.

In FIG. 1, a schematic diagram of a typical well 100 is shown. The well 100 includes sections of casing 102 installed into concentric wellbores 104, such as a conductor casing 106, a surface casing 108 and an intermediate casing 110. It should be appreciated the term casing used herein also includes liners or any other form of a tubular member. The casing 102 extend to varying depths according to the engineering of the well 100 and particularly to the different formations through which the wellbores 104 extend. The well 100 further includes a deviated or horizontal wellbore 109 into which a production casing string 112 is being run in.

With reference to FIG. 2, an apparatus 10, constructed in accordance with the present invention, is shown engaged with the casing string 112 and positioned within a previously installed section of casing, such as the intermediate casing 110. The casing string 112 is generically illustrated for exemplary purposes only. The apparatus 10 is a piston assembly 10 including a piston body 12 having a forward end 14 and a rearward end 16. The piston body 12 further defines a radial shoulder surface 18, which is of a diameter to correspond to the I.D. of the intermediate casing 110 such that a sealing contact is made between the radial shoulder surface and the intermediate casing. The radial shoulder surface 18 includes a wear surface 20 and a sealing surface 22.

To aid in centralizing the piston assembly 10, a centralizing member 114 can be engaged with the casing string 112, and depending upon where the piston assembly 10 is engaged along the casing string 112, a centralizing member can be used forward and rearward of the piston assembly. The centralizing member 114 is a mechanical device to position casing concentrically in a wellbore. Usable centralizing members 114 are well known in the art and do not need to be described herein.

Preferably, the piston assembly 10 is engaged with the casing string 112 between the liner hanger, not shown but well known in the art, from which production casing depends (not shown) and the second to the last joint of pipe, in the casing string, required to land the liner hanger in its engineered well position within the intermediate casing 110.

Now with reference to FIGS. 3 and 4, a partial cross-section of the piston assembly 10 engaged with the casing string 112 and positioned within the intermediate casing 110 is shown. The piston assembly 10 further includes a mandrill 24 and an adaptor sub 26. The adaptor sub 26 and the mandrill 24 allow connection of the piston assembly 10 with casing string 112. The mandrill 24 is slidably received through the rearward end 16 of the piston body 12 by a longitudinal bore 28. The mandrill 24 is positionable in a first forward position as shown in FIG. 3 and in a second rearward position as shown in FIG. 4. The mandrill 24 is positioned in the first forward position during running in of the casing string 112 and then positioned in the second rearward position upon completion of running in the casing string. The mandrill 24 when positioned in the first forward position, as shown in FIG. 3, the first end 30 thereof is engaged with the adaptor sub 26 as shown. Preferably, the first end 30 of the mandrill 24 is threadably engaged with the adaptor sub 26.

The piston body 12 further defines at least one blind port hole 32 formed therethrough from an exterior surface 33 forward of the radial shoulder surface 18 to the longitudinal bore 28, and at least one annulus port hole 34 formed therethrough from an exterior surface 35 rearward of the radial shoulder surface to the longitudinal bore. Preferably, four blind port holes 32 and four annulus port holes 34 are formed through the piston body 12 radially therearound and offset at 90 degrees. The blind port holes 32 and the annulus port holes 34 a restricted from fluidic communication when the mandrill 24 is in the first forward position, as shown in FIG. 3, and are in fluidic communication when the mandrill is in the second rearward position, as shown in FIG. 4.

The piston assembly 10 further includes at least one projection 36 extending into the longitudinal bore 28 approximate the rearward end 16 of the piston body 12. Preferably, there are two opposed projections 36. Most preferably, there are four projections 36 spaced radially around the rearward end 16. The projections 36 can be spaced radially around the rearward 16 at an offset of 90 degrees.

A cooperating slot 38 formed longitudinally along the exterior surface 39 of the mandrill 24 receives each projection 36. Each slot 38 is formed along the exterior surface 39 of the mandrill 24, such that when the mandrill is in the first forward position, each projection 36 is free from engagement with the cooperating slot 38 and the mandrill is free to rotate about its axis within the longitudinal bore 28. And such that when the mandrill 24 is in the second rearward position, each projection 36 is engaged with the cooperating slot 38 and the mandrill is rotationally locked with the piston body 12.

A piston body 12 further defines at least one longitudinal passage 40 or channel formed through the radial shoulder surface 18 from the annulus side or rearward side of the radial shoulder surface to the blind or forward side of the radial shoulder surface. A check valve 42 is fitted within each passage 40 and allows fluid to flow from the blind side of the radial shoulder surface to the annulus side of the radial shoulder surface when pressure within the intermediate casing on the annulus side is below a predetermined value.

Additionally a plurality of O-ring seals 44 can be positioned along the longitudinal bore 28 to providing sealing between the mandrill 24 and the interior surface of the longitudinal bore.

In use, it can now be understood, the piston assembly 10 is engaged or otherwise installed inline in the casing string 112 between the casing hanger from which the casing to be installed depends and the second to the last joint of casing string pipe required to land the liner hanger in its engineered well position.

The casing string 112 with the engaged piston assembly 10 is inserted into the intermediate casing 110 using surface equipment well known in the art to a predetermined point. The casing string 112 can be inserted into the intermediate casing to the predetermined point through such methods as gravity feeding or floating, both well known in the art. While these two methods are mentioned, it should be appreciated that other methods can be used to insert the casing string 112. During this process, fluid is free to flow from the blind side of the piston body 12 to the annulus side of the piston body through the passages 40.

Once the casing string 112 with the engaged piston assembly 10 is inserted to the predetermined point, the intermediate casing 110 above the radial shoulder surface 18 is pressurized with a fluid, such a drilling fluid. The intermediate casing 110 can be pressurized with drilling fluid through known techniques and equipment. One such technique that is possible is through the use of drilling fluid pump connected to a source of drilling fluid and to the wellhead through a kill line and other conventional equipment.

The pressurization of the intermediate casing 110 creates a pressure differential across the piston assembly 10 and forces the piston assembly, which is engaged with the casing string 112, to translate through the intermediate casing and into the wellbore 110, thereby pressing production casing attached to the casing string 112 into the wellbore.

Once the casing string 112 has reached a position within the intermediate casing 110 that facilitates landing of the production casing to the intermediate casing, the intermediate casing is depressurized. The pressure cross the piston assembly is then equalized by establishing the blind port holes 32 in fluidic communication with the annulus port holes 34 by moving the mandrill 24 from the first forward position to the second rearward position. Once pressure is equalized across the piston assembly 10, the piston assembly is backed off from the installed production casing and withdrawn from the well 100 using known methods.

A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims. 

1. A method of running in casing into a borehole having a previously installed section of casing is provided, the method including the steps of: (i) providing a piston assembly; (ii) engaging the piston assembly with a casing string to be installed into the borehole; (iii) inserting the casing string with the engaged piston assembly into the previously installed section of casing; and (iv) pressurizing the previously installed section of casing above the piston assembly with a fluid such that the piston assembly engaged with the casing string is forced to translate within the previously installed section of casing causing the casing string to be pressed into the borehole.
 2. The method as recited in claim 1, further comprising the steps of: (v) equalizing pressure across said piston assembly; and (vi) backing off said piston assembly from the casing string.
 3. The method as recited in claim 2, wherein said fluid is drilling fluid.
 4. The method as recited in claim 2, said piston assembly includes: a piston body having a forward end including an adaptor sub and an opposite rearward end, the piston body defining a longitudinal bore formed axially therethrough; a mandrill, said mandrill is slidably received within said longitudinal bore through said rearward end and is slidable within said longitudinal bore to a first forward position and to a second rearward position; said piston body having a radial shoulder surface of a diameter to correspond to an interior diameter of the previously installed casing, such that when said piston body is positioned within the previously installed casing a sealing contact is made between said radial shoulder surface of the piston body and the interior surface of the previously installed casing; and said piston body further defining at least one blind port hole formed therethrough from an exterior surface forward of said radial shoulder surface to said longitudinal bore, and defining at least one annulus port hole formed therethrough from an exterior surface rearward of said radial shoulder surface to the longitudinal bore.
 5. The method as recited in claim 4, wherein during said step (v) equalizing pressure across said piston assembly, said mandrill is moved from said first forward position to said rearward position establishing fluid communication between said blind port hole and said annulus port hole.
 6. The method as recited in claim 1, wherein said casing string includes at least one centralizer engaged therewith.
 7. The method as recited in claim 1, wherein said casing string is a production casing string.
 8. An apparatus for running in a casing string into a borehole having a previously installed section of casing is provided, the apparatus comprising: a piston body having a forward end including an adaptor sub and an opposite rearward end, the piston body defining a longitudinal bore formed axially therethrough; a mandrill, said mandrill is slidably received within said longitudinal bore through said rearward end and is slidable within said longitudinal bore to a first forward position and to a second rearward position; said piston body having a radial shoulder surface of a diameter to correspond to an interior diameter of the previously installed casing, such that when said piston body is positioned within the previously installed casing a sealing contact is made between said radial shoulder surface of the piston body and the interior surface of the previously installed casing; and said piston body further defining at least one blind port hole formed therethrough from an exterior surface forward of said radial shoulder surface to said longitudinal bore, and defining at least one annulus port hole formed therethrough from an exterior surface rearward of said radial shoulder surface to the longitudinal bore.
 9. The apparatus of claim 8, wherein said radial shoulder surface includes a wear surface and a radial seal.
 10. The apparatus of claim 9, wherein said longitudinal bore defines a threaded section approximate said forward end of said piston body and further wherein said mandrill includes a threaded forward end which is adapted to be threadably engaged with said threaded section.
 11. The apparatus of claim 10, further comprising: at one least projection extending into said longitudinal bore approximate said rearward end of said piston body, said at least one projection is adapted to be received by a cooperating slot formed longitudinally along an exterior surface of said mandrill.
 12. The apparatus of claim 11, wherein said cooperating slot is formed along said exterior surface of said mandrill such that when said mandrill is positioned in the first forward position the projection is free from engagement with said slot and such that when said mandrill is positioned in the second rearward position said projection is engaged with said slot.
 13. The apparatus of claim 8, further comprising: a one-way valve positioned within a channel that is formed longitudinal through said radial shoulder.
 14. The apparatus of claim 8, further comprising: at least one o-ring seal positioned in said longitudinal bore to provide sealing contact between said mandrill and the sidewall of said longitudinal bore.
 15. An apparatus for use in running in production casing in a borehole having an intermediate casing already installed therein, the apparatus being adapted to be engaged inline with a production casing string comprising, the apparatus comprising: a piston body having a forward end and an opposite rearward end, the piston body defining a longitudinal bore formed axially therethrough; an adapter sub threadably received by said forward end of said piston body; a mandrill having a first end and an second end, said mandrill is slidably received within said longitudinal bore through said rearward end of said piston body, and is slidable within said longitudinal bore to a first forward position and a second rearward position, said first end of said mandrill is adapted to be threadably coupled to said adapter sub when said mandrill is in the first forward position; said piston body having a radial shoulder of a diameter corresponding to an interior diameter of the intermediate casing, such that when said piston body is positioned within the intermediate casing a sealing contact is made between said radial shoulder surface of said piston body and the interior surface of the intermediate casing; said piston body further defining at least one blind port hole formed therethrough from an exterior surface forward said radial shoulder surface to said longitudinal bore, and defining at least one annulus port hole formed therethrough from an exterior surface rearward of said radial shoulder surface to said longitudinal bore; and wherein fluid communication is established between said at least one blind port hole and said at least one annulus port hole when said mandrill is positioned in said second rearward position.
 16. The apparatus of claim 15, further comprising: at least one projection extending inward into said longitudinal bore approximate said rearward end and which is adapted to be received by a cooperating slot formed longitudinally along an exterior surface of said mandrill.
 17. The apparatus of claim 16, wherein said cooperating slot is formed along said exterior surface of said mandrill such that when said mandrill is positioned in the first forward position the projection is free from engagement with said slot and such that when said mandrill is positioned in the second rearward position said projection is engaged with said slot.
 18. The apparatus of claim 17, further comprising: at least one o-ring seal positioned in said longitudinal bore to provide sealing contact between said mandrill and a sidewall of said longitudinal bore.
 19. The apparatus of claim 18, further comprising: a one-way valve positioned within a channel that is formed longitudinal through said radial shoulder.
 20. The apparatus of claim 15, wherein said radial shoulder includes: a wear surface; and a sealing member. 